Originally Posted by deltaten
I wonder how much drag would be introduced by one of those 'drop-in the stream' hydro-gens? IIRC, they produce some tremendous amounts of power without costing huge dollars or taking up a lot of space.
They produce very little power, typically 100 watts, and that's at 7.8 knotts through the water, which is more than hull speed for a typical cruising sailboat. A more realistic 5 knotts, the output is down to about 50 watts - you can get that from a single solar panel.
With the micro-hydro, it would take several days of continuous operation to recharge the batteries from the use of an electric drive for an hour.